Mobile router device and home agent device

ABSTRACT

In a home agent device, a message reception unit receives a request of deleting a registration of a mobile router device which has become in a non-connection state, a binding cache registration deletion reception unit judges that it is for deleting a mobile router device which is not a transmission source, and if a mobile router device of the transmission source has the authority of deleting the registration of the target mobile router device, a proxy deletion reception judgment unit deletes the registration of the requested mobile router, therefore, it can be prevented that packets are transmitted to the mobile router device which has become in the non-connection state.

This application is a U.S. national phase application of PCTInternational application PCT/JP2005/000106 dated Jan. 7, 2005.

TECHNICAL FIELD

The present invention relates to an address management technologymanaging addresses of a mobile router device on a mobile network, whichmoves between plural networks.

BACKGROUND ART

Conventionally, as a mobile router device and a home agent device, forexample, there exist the ones as disclosed in a specification of U.S.Patent Application No. 2003-0117965. FIG. 15 shows a configuration of acommunication network including the conventional mobile router deviceand the home agent device disclosed in the specification of U.S. PatentApplication No. 2003-0117965.

In FIG. 15, a mobile router device (MR) 1801 and a mobile node (MN) 1802leave a home link 1805 in a state of forming a mobile network 1811 andare connected to a foreign link 1808. Then, the mobile router device(MR) 1801 generates a care-of address based on a router advertisementmessage (hereinafter, written as “RA message”) received from an accessrouter device (AR) 1807 on the foreign link 1808.

Next, the mobile router device 1801 trades a binding update message(hereinafter, written as “BU message”) and the like with a home agentdevice (HA) 1804, and the home agent device 1804 creates a bindingcache. Further, the home agent device 1804 creates a bi-directionaltunnel between the home agent device 1804 and the mobile router device1801.

After the bi-directional tunnel is created, the mobile router device1801 transmits routing information to the home agent device 1804. Then,the home agent device 1804 interprets the routing information andmulticasts the routing information to the home link 1805.

Accordingly, a packet addressed to the mobile node (MN) 1802 from acorrespondent node (CN) 1810 connecting to an internet 1809 are relayedfrom a router 1806 on the home link 1805 to the home agent device 1804,and further, transferred to the mobile router device 1801 using thebi-directional tunnel.

Then, the mobile router device 1801 relayed the transferred packet tothe mobile node 1802 in the mobile network 1811.

Hereupon, a data configuration of an NEMO binding update message isshown in FIG. 8, which is disclosed in an IETF Mobile IP WG internetdraft “Network Mobility (NEMO) Basic Support Protocol”. Note that theNEMO binding update message is formed by extending a mobile IPv6 bindingupdate message disclosed in an IETF Mobile IP WG internet draft“Mobility Support in IPv6”.

In FIG. 8, when transmitted from the mobile router device 1801 in amovement destination to the home agent device 1804, a care-of address ofthe mobile router device 1801 is set in a source address 801, and aglobal address of the home agent device 1804 is set in a destinationaddress 802. And a home address of the mobile router device 1801 is setin a home address 803 of a destination option header. Further, thecare-of address of the mobile router device 1801 is set in a proxycare-of address 804 of a mobility header, and valid time of theseinformation is set in units of seconds in a lifetime 805.

The home agent device 1804 registers the care-of address in the bindingcache, associating it with the home address of the mobile router device1801 based on these information. FIG. 7A is a binding cache tableshowing a data structure of information registered in the binding cache.

In FIG. 7A, according to a home address 701, a registered mobile routerdevice is specified, and associated with a care-of address 702 in theforeign link where the mobile router is currently located. Further, aprefix 703 showing a network address unit of a mobile network to whichthe mobile router device belongs and a valid time 704 showing availableduration of the mobile router device are registered, being associatedwith the home address 701.

However, when the mobile router device 1801 is replaced with anothermobile router device, it is necessary that the BU message in which “0”is set in the lifetime 805 is sent to the home agent device 1804 fromthe previously used mobile router device 1801 to delete data registeredin the binding cache. However, the mobile router device 1801 can notsend the BU message to the home agent device 1804 when it has alreadycut the connection to the foreign link. Thus, the home agent devicecontinues sending messages addressed to the mobile node which waspreviously under the mobile router device 1801 to the mobile routerdevice 1801 in accordance with information registered in the bindingcache until the time which has been set in the lifetime 805 has passed.However, the mobile router device 1801 is not connected to the foreignlink 1808, the transmitted packets do not reach the mobile node 1802 andvanish.

DISCLOSURE OF THE INVENTION

An object of the invention is to provide a mobile router device and ahome agent device, in which a registration in a binding cache of thehome agent device can be updated immediately when the mobile routerdevice connecting to a foreign link of a movement destination isreplaced.

The mobile router device of the present invention includes a receptionunit receiving a request for deleting a registration from the mobilerouter device which has been registered in the binding cache of the homeagent device and a BC registration deleting request unit requesting thehome agent device to delete the registration of the mobile router deviceon receipt of the received request.

According to the above, the request of a proxy deletion from anothermobile router in the same mobile network can be transmitted to the homeagent.

In addition, the mobile router device of the invention includes anetwork connection management unit detecting a connection state with anexternal link in the mobile router device other than itself, which isconnected to the same internal link and a proxy deleting request unitrequesting the home agent device to delete the registration of themobile router device when the network connection management unit detectsa non-connection state with the external link in the mobile routerdevice other than itself.

According to the above, the proxy deletion can be requested to the homeagent device without receiving the request of registration deletion fromanother mobile router, therefore, another mobile router device does nothave to be provided with a particular function for requesting the proxydeletion.

The home agent deice of the present invention includes a messagereception unit receiving a request for deleting the registration of themobile router device from the binding cache, a BC registration deletionreception unit judging whether the deletion request from a first mobilerouter device is a proxy deletion for deleting the registration of asecond mobile router device or not, and a proxy deletion receptionjudgment unit judging whether the first mobile router has beenregistered in advance as the one having the authority of deleting theregistration of the second mobile router device or not, and the BCregistration deletion reception unit deletes the registration of thesecond mobile router device from the binding cache in the case that thedeletion request is the proxy deletion and the first mobile routerdevice has the authority of the proxy deletion.

According to the above, only the proxy deletion request from thepreviously authorized mobile router is received and the registration ofthe designated mobile router device can be deleted, therefore, theregistration deletion of the mobile router device with malicious intentcan be prevented.

Additionally, the home agent device of the invention includes akey/authentication storage unit previously storing information,associating it with keys performing decryption, which concerns a firstmobile router device having the authority of performing a proxy deletionfor the registration of a mobile router device other than itself from abinding cache and a second mobile router device to be deleted by proxy,an authentication unit extracting a corresponding key from thekey/authentication storage unit based on information of the first mobilerouter device which is a transmission source of a received encryptedmessage and the second mobile router device designated by the firstmobile router device, a decryption unit decrypting the encrypted messageby means of the extracted key and a BC registration deletion receptionunit deleting the registration of the second mobile router device fromthe binding cache in the case that the decrypted message from the firstmobile router device is a deletion request for the second mobile router.

According to the above, even when the encrypted communication isperformed with the mobile router device, only the request from themobile router device having the proper authority of the proxyregistration deletion can be received.

According to the invention as the above, when the mobile router deviceconnecting to the external link is replaced, it is prevented that thehome agent device transmits a packet to the mobile router device in thenon-connection state. In addition, the binding cache of the home agentdevice can be used efficiently.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a configuration of a home agent deviceaccording to an embodiment 1 of the invention.

FIG. 2 is a block diagram showing a configuration of a mobile routerdevice according to the embodiment 1 of the present invention.

FIG. 3 is a flowchart showing the operation of the home agent accordingto the embodiment 1 of the present invention.

FIG. 4 is a flowchart showing the operation of the mobile router deviceaccording to the embodiment 1 of the present invention.

FIG. 5 is a flowchart showing the operation of the home agent accordingto the embodiment 1 of the present invention.

FIG. 6 is a block diagram showing a configuration of a communicationnetwork according to the embodiment 1 of the present invention.

FIG. 7A is a table indicating a data configuration of a binding cache ofthe home agent device according to the embodiment 1 of the invention.

FIG. 7B is a table indicating a data configuration of the binding cacheof the home agent device according to the embodiment 1 of the invention.

FIG. 7C is a table indicating a data configuration of the binding cacheof the home agent device according to the embodiment 1 of the invention.

FIG. 8 is a chart indicating a format of a binding update messageaccording to the embodiment 1 of the invention.

FIG. 9A is a chart indicating another format of the binding updatemessage according to the embodiment 1 of the invention.

FIG. 9B is a chart indicating an encrypted binding update messageaccording to an embodiment 3 of the invention.

FIG. 10 is a block diagram showing a configuration of a mobile routerdevice according to an embodiment 2 of the invention.

FIG. 11 is a block diagram showing a configuration of a home agentdevice according to the embodiment 3 of the invention.

FIG. 12 is a block diagram showing a configuration of a mobile routerdevice according to the embodiment 3 of the invention.

FIG. 13 is a flowchart showing the operation of the home agent deviceaccording to the embodiment 3 of the invention.

FIG. 14 is a flowchart showing the operation of the mobile router deviceaccording to the embodiment 2 of the invention.

FIG. 15 is a block diagram showing a configuration of a conventionalcommunication network.

DESCRIPTION OF REFERENCE NUMERALS

-   -   101 data link interface    -   102 IP processing unit    -   103 BC registration reception unit    -   104 BC registration deletion reception unit    -   105 binding cache    -   106 proxy deleting judgment unit    -   107 proxy deletion MR storage unit    -   201 external link interface    -   202 internal link interface    -   203 IP processing unit    -   204 network connection judgment unit    -   205 BC registration request unit    -   206 BC registration deleting request unit    -   207 proxy deleting judgment unit    -   208 MR list storage unit    -   209 proxy deleting request unit    -   601, 602, 1801 mobile router device (MR)    -   603, 1802 mobile node (MN)    -   604, 1803 internal link    -   605, 1804 home agent device (HA)    -   606, 1805 home link    -   607, 1806 router    -   608, 610, 1807 access router (AR)    -   609, 611, 1808 foreign link    -   612, 1809 internet    -   613, 1810 correspondent node (CN)    -   614, 1811 mobile network    -   1001 network connection management unit    -   1101 decryption unit    -   1102 SPI storage unit    -   1201 encryption unit    -   1202 key storage unit        Best Mode for Carrying Out the Invention

Hereinafter, embodiments of the invention will be explained withreference to the drawings.

Embodiment 1

The configuration of a communication network according to an embodimentof the invention is shown in FIG. 6.

In FIG. 6, a mobile router device (MR1) 601 and a mobile router device(MR2) 602 form a mobile network 614 with a mobile node (MN) 603 and aninternal link 604, connecting to a home link 606 managed by a home agentdevice (HA) 605. The home link 606 connects to an internet 612 through arouter device 607, and communication can be possible with acorrespondent node (CN) 613.

Then, the mobile network 614 leaves the home link 606 and connects to aforeign link 609 under an access router (AR1) 608. At this time, themobile router device (MR1) 601 connects to the foreign link, however,the mobile router device (MR2) 602 does not connect to that.

Further, the mobile network 614 moves and connects to a foreign link 611under an access router (AR2) 610. At this time, the mobile router device(MR2) 602 connects to the foreign link 611, however, the mobile routerdevice (MR1) 601 does not connect to that. Note that a prefix of theinternal link in the mobile network 614 is 4::/64, a prefix of the homelink is 1::/64, a prefix of the foreign link under the AR1 is 2::/64,and a prefix of the foreign link under the AR2 is 3::/64. Further, ahome address of the mobile router device (MR1) is 1::3, the one of themobile router device (MR2) is 1::4, and a local address of the MN is4::2. For the mobile routers MR1, MR2, the home link and foreign linkscorrespond to external links.

First, the configuration and operation of the home agent device and themobile router device in such mobile communication system will beexplained below.

FIG. 1 is a block diagram showing a configuration of the home agentdevice according to the embodiment of the invention.

In FIG. 1, a data-link interface (data link i/f) 101 performscommunication processing in a physical layer and a data-link layer, andan IP processing unit 102 performs IP protocol processing in a networklayer. A binding cache 105 is a memory which saves home addresses andcare-of addresses of managing mobile router devices, a BC registrationreception unit 103 registers the care-of address in the binding cache105 by associating it with the home address of the mobile router device,which is notified by a BU message from the mobile router device, and aBC registration deletion reception unit 104 deletes the registration ofthe mobile router device from the binding cache 105 based on informationof the BU message from the mobile router device. A proxy deletion MRstorage unit 107 stores the mobile router device having the authority ofdeleting the registration of another mobile router from the bindingcache instead of the mobile router to be deleted itself, and a proxydeleting judgment unit 106 judges whether a request is a proxy deletionrequest from the mobile router device stored in the proxy deletion MRstorage nit 107 or not. Note that the data-link interface 101 and the IPprocessing unit 102 correspond to a message reception unit.

The operation and effect of the home agent device constructed asdescribed above will be explained below with reference to FIG. 3.

First, the IP processing unit 102 judges whether it has received a BUmessage (BUM) from the data-link interface 101 or not (step S301), whenreceived, the IP processing unit 102 checks a life time 805, and makes anotification to the BC registration deletion reception unit 104 in thecase that the life time 805 is “0” (step S302).

The BC registration deletion reception unit 104 receives thenotification and checks that the BU message is a deletion request from aproxy mobile router device (step S303). The judgment whether the proxydeletion request or not is performed based on whether a source address801 of a BU message IPv6 header corresponds to a proxy care-of address804 of a mobility header shown in FIG. 8. In the case that the proxycare-of address 804 corresponds to the source address 801, the BCregistration deletion reception unit 104 judges that a request source isthe mobile router device itself to be deleted from the binding cache,and deletes information concerning the mobile router device of therequest source from the binding cache 105 (step S305).

On the other hand, the BC registration deletion reception unit 104, whenjudging that the deletion request is the one from a proxy mobile router,instructs the proxy deleting judgment unit 106 to check whether themobile router device of the request source has qualification of theproxy deletion or not. The proxy deleting judgment unit 106 receives theinstruction, then, judges whether the mobile router device which isintended for the deletion is stored in the proxy deletion MR storageunit 107, and whether the mobile router device of the transmissionsource of the BU message is stored as the mobile router device which hasauthority of deleting the target mobile router device (step S304). Ifstored, the proxy deleting judgment unit 106 notifies the BCregistration deletion reception unit 104 accordingly, and the BCregistration deletion reception unit 104 deletes information of themobile router device of which deletion is requested from the bindingcache 105 (step S305). If not stored in the proxy deletion MR storageunit 107, the processing ends without deleting information of the mobilerouter device of which deletion is requested.

According to the above, the home agent device deletes the mobile routerdevice which has become in a non-connection state from the binding cacheby the proxy deletion request of the mobile router device registered inadvance.

The processing of the proxy deletion reception by the limited mobilerouter device is not essential, however, it is effective for preventingimproper deletion of registration of another mobile router, orpreventing the registration deletion with malicious intent.

Next, the configuration of the mobile router device according to theembodiment of the invention will be explained below with reference toFIG. 2.

In FIG. 2, an external link interface (external link i/f) 201 performscommunication processing in the physical layer and the data-link layerconnecting to the home link and the foreign link, and an internal linkinterface (internal link i/f) 202 performs communication processing inthe physical layer and the data-link layer connecting to the internallink, and an IP processing unit 203 performs IP protocol processing inthe network layer. In addition, a network connection judgment unit 204judges whether it is in the connection state with the external link orthe home link, a BC registration request unit 205 instructs the IPprocessing unit 203 to send a BU message requesting a registration ofinformation of itself in the binding cache to the home agent device, anda BC registration deleting request unit 206 instructs the IP processingunit 203 to send a BU message requesting the deletion of information ofdesignated mobile router device from the binding cache to the home agentdevice. And a proxy deleting judgment unit 207 judges whether the mobilerouter device which has asked the home agent device to request the proxydeletion is stored in a MR list storage unit 208 or not. A proxydeleting request unit 209 asks another mobile router device set inadvance to send a request of deleting the registration of itself fromthe home agent. Note that the external link interface 201, the internallink interface 202 and the IP processing unit 203 correspond to thereception unit relating to the invention.

The operation and effect of the mobile router device constructed asdescribed above will be explained below with reference to FIG. 4 andFIG. 5.

First, the IP processing unit 203 checks whether it has received a RAmessage from the router device 607 through the interface 201 or not,when received, the IP processing unit 203 make a notification to thenetwork connection judgment unit 204 (step S401). The network connectionjudgment unit 204 generates a care-of address from the information (stepS402).

Next, the network connection judgment unit 204 judges whether thecare-of address has been notified to the home agent device or not (stepS403), when judged that it has been notified, the processing ends. Whenjudged that the registration to the home agent has not been performedyet, the network connection judgment unit 204 instructs the BCregistration request unit 205 to make a registration in the bindingcache of the home agent device. The BC registration request unit 205received the instruction and sends the BU message shown in FIG. 8, inwhich the new care-of address is set to the proxy care-of address, tothe home agent device through the external link interface 201 (stepS404).

On the other hand, in the step S401, (when/if) the IP processing unit203 has not received the RA message, the network connection judgmentunit 204 judges the non-connection with the external link, because thereis no reception notification of RA message from the IP processing unit203 after the prescribed time has passed (step S401). At this time, thenetwork connection judgment unit 204 judges whether the care-of addressof itself has been registered in the binding cache of the home agentdevice or not (step S405), if not registered, the processing ends. Whenregistered, the network connection judgment unit 204 instructs the proxydeleting judgment unit 207 to send a message requesting another mobilerouter device connecting to the internal link for a proxy deletionrequest. On the receipt of the instruction, the proxy deleting requestunit 209 sends the request of the proxy deletion from the binding cacheof the home agent device to the mobile router device designated inadvance, which has the authority of deleting the registration of itselfthrough the internal link interface 202 (step S406).

Next, processing when the proxy request from another mobile routerconnecting to the internal link has been received will be explained withreference to FIG. 5.

First, the IP processing unit 203 receives a proxy deletion message fromanother mobile router device through the internal link interface 202(step S501), then, notifies the reception to the proxy deleting judgmentunit 207. The proxy deleting judgment unit 207 judges whether the sourceaddress of the proxy deletion message is the mobile router device storedin the MR list storage unit 208 or not (step S502), if not stored, theproxy deleting judgment unit 207 ignores the message.

On the other hand, when the message is sent from the mobile routerdevice stored in the MR list storage unit 208, the proxy deletingjudgment unit 207 instructs the BC registration deleting request unit206 to request the proxy deletion with respect to the home agent device.

On the receipt of the instruction, the BC registration deleting requestunit 206 instructs the IP processing unit 203 to send a BU message tothe home agent device, in which the care-of address of itself, theaddress of the home agent device, the home address of itself and thecare-of address of the mobile router which has requested theregistration deletion from the home agent are respectively setcorresponding to the source address 801, the destination address 802,the home address 803, and the proxy care-of address in the BU messageshown in FIG. 8, and further “0” is set to the lifetime 805.

On receipt of the instruction, the IP processing unit 203 send the BUmessage to the home agent device through the external link interface 201(step S503).

According to the above, the mobile router device can delete theregistration of itself from the home agent by requesting another mobilerouter connecting to the internal link for the proxy deletion when theconnection with the external link is cut off.

It is also possible that the mobile router device can delete theregistration of the mobile router device of the request source which isin the home agent on receipt of the request of the proxy deletion fromanother mobile router device connecting to the internal link.

Note that it is not essential for the mobile router device to have boththe function of requesting the proxy deletion and the function ofreceiving the proxy deletion, and the function of receiving the proxydeletion may be limited to the mobile router which has registered in thehome agent device in advance.

Next, the operation between each other when plural mobile routers asdescribed above move to the foreign links 609, 611 from the home link606 as shown in FIG. 6 will be explained below.

First, the home agent device 605 detects that the RA message from themobile router device (MR1, MR2) is not issued, and recognize that theseare not connected to the home link 606.

Next, the mobile router device (MR1) 601 connects to the foreign link609 and acquires a care-of address (2::3) from the access router (AR1)608, then, notifies it to the home agent device by means of the BUmessage. The home agent device 605 generates the binding cache as shownin FIG. 7B, in which a care-of address 706 is registered by associatingit with a home address 705 of the mobile router device (MR1). Since themobile router device MR2 is not connected, it is not registered in thehome agent device.

Next, when the mobile network 614 further moves and connects to theforeign link 611, the mobile router device (MR2) acquires a care-ofaddress (3::4) from the AR2. The mobile router device (MR2) notifies itto the home agent device (HA) 605 by means of the BU message. On thereceipt of the notification, the home agent device (HA) 605 registers acare-of address 708, associating it with a home address 707 of themobile router device (MR2) in the binding cache as shown in FIG. 7C.

Then, the mobile router device (MR1) detects that it does not connect tothe foreign link, and asks the mobile router device (MR2) for therequest of the proxy deletion with respect to the home agent (HA) viathe internal link. On receipt of the request, the mobile router device(MR2) requests the home agent device (HA) to delete the registration ofthe mobile router device (MR1) from the binding cache. The home agentdevice (HA) receives the request and deletes information of the mobilerouter device (MR1) from the binding cache.

In the embodiment, the mobile router device (MR2) generates the BUmessage for the proxy deletion by receiving the request from the mobilerouter device (MR1), however, it is not limited to that and is alsopossible that the mobile router device (MR1) send a message having thesame format as the BU message to the mobile router device (MR2) throughthe internal link, then, the mobile router device (MR2) tunnel-forwardsthe message with an IPv6 header added to it as an encapsulated tunnelpacket to the home agent. The message sent from the mobile router (MR1)to the mobile router device (MR2) is explained as follows.

Specifically, 2::3 as the care-of address of the mobile router device(MR2) is set in the source address 801, and 1::2 as the home device isset in the destination address 802. Further, 1::3 is set as the homeaddress 803 in a destination option header, “0” is set in a lifetime 806in a mobility header, and 2::3 is set in the proxy care-of address 804.

The format of the BU message forwarded from the mobile router device(MR2) to the home agent device (HA) by tunneling is the one with an IPv6header 901 added to it as shown in FIG. 9A, in which the care-of address(3::4) of the mobile router device (MR2) is set in the source address,and the address of the home agent device (HA) (1::2) is set in thedestination address. The home agent device which has received the packetanalyzes the IPv6 header 901 and judges that the packet has beentunnel-forwarded. Then, the home agent device (HA) removes the outsideof the IPv6 header 901. As a result, the home agent device (HA)processes the message as a normal BU message from the mobile routerdevice (MR1) having the care-of address of 2::3, because the destinationof the inside of the packet is 1::2 which is the address of the homeagent device.

According to the above, the registration of the mobile router devicewhich becomes in the non-connection state can be deleted from thebinding cache of the home agent device (HA), therefore, the bindingcache of the home agent can be used efficiently and it can be preventedthat the home agent device transmits packets to the mobile router devicewhich is in the non-connection state.

In the embodiment, the mobile router device performs the proxy requestfor the registration deletion to the home agent device by using the BUmessage, therefore, the mobile router device is not required to use aparticular message and is only required to have a normal IPv6specification.

Embodiment 2

FIG. 10 is a block diagram showing a configuration of a mobile routerdevice according to an embodiment 2 of the invention.

The device is different from the mobile router device in the embodiment1 at the point of including a network connection management unit 1001instead of the network connection judgment unit 204 and at the point ofnot including the proxy deleting judgment unit 207 and the MR liststorage unit 208.

FIG. 14 is a flow chart showing the operation of the mobile routerdevice in the embodiment. This FIG. 14 is an alternative of theprocessing shown in FIG. 5 of the embodiment 1, in which the proxyrequest is received from the another mobile router device connecting tothe same internal link.

In FIG. 14, first, the network connection management unit 1001 watchesout for RA messages of the mobile router devices connecting to the sameinternal link as itself, and detects the mobile router device from whichthe RA message has not been received after the prescribed time haspassed. Then, the network connection management unit 1001 judges thatthe detected mobile router device has disconnected from the externallink and notifies it to the proxy deleting request unit 209 (stepS1401).

The proxy deleting request unit 209 receives the notification, andinstructs: the IP processing unit 203 to send a BU message of the proxydeletion for deleting the registration of the detected mobile routerdevice from the binding cache of the home agent device in the same wayas the embodiment 1. The operation of the IP processing unit 203 whichhas received the instruction is the same as the embodiment 1 (stepS1402).

Accordingly, the mobile router device of the embodiment can perform theproxy deletion of the mobile router which has connected to the externallink to which the mobile router itself is connected, therefore theanother mobile router device is not required to have the networkconnection judgment unit 204 and the proxy deleting request unit 209. Inthe embodiment, the case of not including the proxy deleting judgmentunit 207 and the MR list storage unit 208 is shown, however, it is notlimited to that and is also possible that the detected mobile routerdevice is judged whether it is the mobile router device stored in the MRlist storage unit 208 or not, and the proxy deletion request isperformed only with respect to the stored mobile router device.Consequently, only the specific mobile router device can be deleted byproxy, therefore, it can be prevented that the mobile router of whichregistration should be maintained is deleted.

In the embodiment, the proxy deletion request with respect to all themobile routers which become in the non-connection state will betransmitted, however, it is not limited to that and is also possiblethat only the mobile router device can be deleted by proxy, which hastransmitted data other than the RA message just before the connection tothe foreign link is cut. Accordingly, only the registration of themobile router device having the possibility that packets arecontinuously transmitted from the correspondent node is deleted,therefore, packet loss can be efficiently prevented.

According the above, in FIG. 6, in the case that the mobile routerdevice (MR2) 602 is the mobile router device in the embodiment, themobile router device (MR1) 601 is not required to request the mobilerouter device (MR2) 602 for the proxy deletion when the mobile routermoves from the foreign link 609 to the foreign link 611.

Furthermore, the mobile router device of the invention detects theconnection state by the presence of the RA message sent from anothermobile router device, therefore, the mobile router device other than themobile router which detects the connection state is only required tohave a normal IPv6 specification.

Note that the home agent device is the same as the embodiment 1.

Embodiment 3

FIG. 11 is a block diagram showing a configuration of a home agentdevice in an embodiment 3 of the invention.

The device is different from the home agent device in the embodiment 1at the point of including a decryption unit 1101 and a SPI storage unit1102 and at the point of not including the proxy deleting judgment unit106 and the proxy deletion MR storage unit 107.

In FIG. 11, the decryption unit 1101 is the unit for communicating withthe mobile router device in the transport mode by an IPsec, and decryptsthe received encrypted message. A format of the encrypted BU message isshown in FIG. 9B.

The format is prescribed in “draft-ietf-mobileip-ipv6-24.txt”, in whicha mobility header 905 is encrypted in ESP (Encapsulating SecurityPayload) for the protection.

The SPI storage unit 1102 corresponds to a key/authentication storageunit, storing keys for decrypting the encryption by associating themwith a SPI (Security Parameter Index) which is given to each mobilerouter device peculiarly and with the home address of the mobile routerdevice of which authority of the proxy deletion belongs to the mobilerouter corresponding to the SPI.

The decryption unit 1101 corresponds to a authentication unit and adecryption unit according to the invention, and decides the key from theSPI storage unit 1102 based on a destination address of an IPv6 header902 (the address of the home agent device in the embodiment) and a SPIvalue included in an ESP header 904. At the same time, the decryptionunit 1101 checks whether the home address included in a destinationoption header 903 is the mobile router device registered in the SPIstorage unit 1102 or not, and when it is the home address of theregistered mobile router device, the decryption is performed, however,when it is not registered, the decryption is not performed.

Next, the operation of the home agent device will be explained withreference to FIG. 13.

First, the IP processing unit 102 judges whether the received message isencrypted one or not (step S1301), when it is not encrypted, theprocessing proceeds to step S1303. On the other hand, in the case thatit is the encrypted message, the IP processing unit 102 instructs thedecryption unit 1101 to perform decryption processing. On receipt of theinstruction, the decryption unit 1101 decrypts the message and notifiesit to the IP processing unit 102 (step S1302).

Next, the IP processing unit 102 judges whether the message is the BUmessage or not (step S1303), and when it is the BU message requestingfor the registration deletion, the IP processing unit 102 notifies it tothe BC registration deletion reception unit 104 (step S1304).

Next, on the reception of the notification, in the case that thedecrypted message is the request of the proxy deletion from the mobilerouter other than the mobile router device to be deleted, the BCregistration deletion reception unit 104 deletes the registration of themobile router device of which the deletion is requested, which isregistered in the binding cache 105, and deletes the registration of themobile router of the transmission source in the case that the message isthe request for the deletion of the mobile router device itself of therequest source (step S1305).

According to the above, the home agent device can perform the proxydeletion using the BU message after judging the advisability for theproxy deletion by the encrypted key.

Next, the mobile router device in the embodiment will be explained. FIG.12 is a block diagram showing a configuration of a mobile router devicein the embodiment 3 of the invention.

It is different from the mobile router device in the embodiment 2 shownin FIG. 10 at the point of including an encryption unit 1201 and a keystorage unit 1202.

In FIG. 12, the encryption unit 1201 encrypts the BU message formed inthe IP processing unit 203 using a key stored in the key storage unit1202 as described above. The key used at the time is same as the onestored in the SPI storage unit 1102 of the home agent device.

The operation of the mobile router device is same as the embodiment 2except that the BU message of the BC registration request is encryptedwhen transmitted at the step S404 in FIG. 4 and that the proxyregistration deletion message is encrypted when transmitted at the stepS503 in FIG. 5.

By using the above home agent device and the mobile router device, evenwhen the mobile network moves while the encrypted communication isperformed between each other, the registration of the mobile routerdevice which is in the non-connection state can be deleted from thebinding cache of the home agent device (HA) in the same way as theembodiment 1. Accordingly, the binding cache of the home agent devicecan be efficiently used and it is prevented that the home agent devicetransmits packets to the mobile router device which is in thenon-connection state.

INDUSTRIAL APPLICABILITY

The present invention is useful for a mobile router device constitutinga mobile network which moves between plural networks and a home agentdevice accommodating the mobile router devices, and preferable for anaddress management when replacing the mobile router device connecting toan external link.

1. A mobile router device, comprising: a mobile router reception unitfor receiving a first request from an other mobile router device fordeleting a registration of the other mobile router device which has beenregistered in a binding cache of a home agent device, the mobile routerdevice and the other mobile router device forming a mobile network, themobile network leaving or having lea a home link and connecting to aforeign link, the other mobile router device not connecting to theforeign link; and a judgment unit for judging whether the first requesthas been made from the other mobile router device which has beenpreviously registered; and a binding cache registration deleting requestunit for providing a second request to the home agent device to deletethe registration of the other mobile router device on receipt of thefirst request, when the other mobile router device has been previouslyregistered and ignoring the first request, when the other mobile routerdevice has not been previously registered.
 2. The mobile router deviceaccording to claim 1, wherein said binding cache registration deletingrequest unit provides said second request to delete the registration ofthe other mobile router when receiving a notification from said judgmentunit, that the first request is sent from the registered mobile routerdevice.
 3. A mobile router device, comprising: a mobile router networkconnection management unit detecting a connection state to an externallink in an other mobile router device other than itself, which connectsto the same internal link; a reception unit for receiving a firstrequest from the other mobile router device for deleting a registrationof the other mobile router device in a binding cache of a home agentdevice, the mobile router device and the other mobile router deviceforming a mobile network, the mobile network leaving or having left ahome link and connecting to the external link, the other mobile routerdevice not connecting to the external link; and a judgment unit forjudging whether the first request has been made from the other mobilerouter device which has been previously registered; and a proxy deletingrequest unit for: (1) providing a second request to the home agentdevice to delete a registration of the other mobile router device when(i) said network connection management unit detects a non-connectionstate to the external link in the other mobile router device other thanitself, and (ii) the other mobile router device has been previouslyregistered; and (2) ignoring the first request when the other mobilerouter device has not been previously registered.
 4. The mobile routerdevice according to claim 3, wherein the detection of the connectionstate is performed by a presence of a router advertisement messagetransmitted from another mobile router device.
 5. The mobile routerdevice according to claim 1, wherein the second request of deleting theregistration is performed by a binding update message designating a homeaddress of the other mobile router device of which registration isdeleted.
 6. The mobile router device according to claim 2, wherein thesecond request of deleting the registration is performed by a bindingupdate message designating a home address of the other mobile routerdevice of which registration is deleted.
 7. The mobile router deviceaccording to claim 3, wherein the second request of deleting theregistration is performed by a binding update message designating a homeaddress of the mobile router device of which registration is deleted. 8.The mobile router device according to claim 4, wherein the secondrequest of deleting the registration is performed by a binding updatemessage designating a home address of the mobile router device of whichregistration is deleted.
 9. A home agent device comprising: a messagereception unit receiving a deletion request for deleting a registrationof a first mobile router device from a binding cache of the home agentdevice; a binding cache registration deletion reception unit judgingwhether the deletion request from a second mobile router device is aproxy deletion for deleting the registration of the first mobile routerdevice when the first mobile router device detects a non-connectionstate to an external link; and a proxy deletion reception judgment unitjudging whether the second mobile router device has been previouslyregistered as one having authority of deleting the registration of thefirst mobile router device, wherein said binding cache registrationdeletion reception unit deletes the registration of the first mobilerouter device from the binding cache of the home agent device if thedeletion request is the proxy deletion and the second mobile routerdevice has the authority.
 10. A home agent device comprising: a homeagent device key/authentication storage unit previously storinginformation, associating the information with keys performingdecryption, which concerns a first mobile router device having authorityof performing a proxy deletion for a registration of a second mobilerouter device other than itself from a binding cache of the home agentdevice and the second mobile router device to be deleted by proxyresponsive to a non-connection state of the second mobile router deviceto an external link is detected; an authentication unit extracting acorresponding key from said key/authentication storage unit based oninformation of the first mobile router device which is a transmissionsource of a received encrypted message and the second mobile routerdevice designated by the first mobile router device; a decryption unitdecrypting the encrypted message by the extracted key; a proxy deletionreception judgment unit judging whether the first mobile router devicehas been previously registered as one having authority of deleting theregistration of the second mobile router device; and a binding cacheregistration deletion reception unit deleting the registration of thesecond mobile router device from the binding cache of the home agentdevice if the decrypted message from the first mobile router device is adeletion request for the second mobile router device and the firstmobile router device has the authority of deleting the registration ofthe second mobile router device.
 11. The home agent device according toclaim 9, wherein the deletion request is a binding update messagedesignating a home address of the first mobile router device.
 12. Thehome agent device according to claim 10, wherein the deletion request isa binding update message designating a home address of the second mobilerouter device.